﻿/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

using System;
using System.Net;
using System.Threading;

namespace Hackerzhuli.Code.Editor.Messaging
{
    internal class TcpListener
    {
        private const int ListenTimeoutMilliseconds = 5000;

        public static int Queue(byte[] buffer)
        {
            var tcpListener = new System.Net.Sockets.TcpListener(IPAddress.Any, 0);
            var state = new State { Buffer = buffer, TcpListener = tcpListener };

            try
            {
                tcpListener.Start();

                var port = ((IPEndPoint)tcpListener.LocalEndpoint).Port;

                ThreadPool.QueueUserWorkItem(_ =>
                {
                    var listening = true;

                    while (listening)
                    {
                        var handle = tcpListener.BeginAcceptTcpClient(OnIncomingConnection, state);
                        listening = handle.AsyncWaitHandle.WaitOne(ListenTimeoutMilliseconds);
                    }

                    Cleanup(state);
                });

                return port;
            }
            catch (Exception)
            {
                Cleanup(state);
                return -1;
            }
        }

        private static void OnIncomingConnection(IAsyncResult result)
        {
            var state = (State)result.AsyncState;

            try
            {
                using (var client = state.TcpListener.EndAcceptTcpClient(result))
                {
                    using (var stream = client.GetStream())
                    {
                        stream.Write(state.Buffer, 0, state.Buffer.Length);
                    }
                }
            }
            catch (Exception)
            {
                // Ignore and cleanup
            }
        }

        private static void Cleanup(State state)
        {
            state.TcpListener?.Stop();

            state.TcpListener = null;
            state.Buffer = null;
        }

        private class State
        {
            public byte[] Buffer;
            public System.Net.Sockets.TcpListener TcpListener;
        }
    }
}